Comparison of physiological and behavioral responses to fresh and thawed breastmilk in premature infants--a preliminary study

Testing detectability, attractivity, hedonic specificity, extractability, and robustness of colostrum odor-Toward an olfactory bioassay for human neonates

Human milk odor is attractive and appetitive for human newborns. Here, we studied behavioral and heart-rate (HR) responses of 2-day-old neonates to the odor of human colostrum. To evaluate detection in two conditions of stimulus delivery, we first presented the odor of total colostrum against water. Second, the hedonic specificity of total colostrum odor was tested against vanilla odor. Third, we delivered only the fresh effluvium of colostrum separated from the colostrum matrix; the stability of this colostrum effluvium was then tested after deep congelation; finally, after sorptive extraction of fresh colostrum headspace, we assessed the activity of colostrum volatiles eluting from the gas chromatograph (GC). Regardless of the stimulus-delivery method, neonates displayed attraction reactions (HR decrease) as well as appetitive oral responses to the odor of total colostrum but not to vanilla odor. The effluvium separated from the fresh colostrum matrix remained appetitive but appeared labile under deep freezing. Finally, volatiles from fresh colostrum effluvium remained behaviorally active after GC elution, although at lower magnitude. In sum, fresh colostrum effluvium and its eluate elicited a consistent increase in newborns' oral activity (relative to water or vanilla), and they induced shallow HR decrease. Newborns' appetitive oral behavior was the most reproducible response criterion to the effluvium of colostrum. In conclusion, a set of unidentified volatile compounds from human colostrum is robust enough after extraction from the original matrix and chromatographic processing to continue eliciting appetitive responses in neonates, thus opening new directions to isolate and assay specific volatile molecules of colostrum.

Effect of Feeding Fresh or Frozen Breast Milk on the Gut Microbiota of Premature Infants: A Prospective Observational Study

BACKGROUND

Breast milk is essential for premature infants. It contains a variety of functional and protective nutrients that help to create a suitable microenvironment for intestinal development and maturation. This prospective and observational study was planned to examine the effects of feeding premature infants with fresh or frozen breastmilk on their gut microbiota.

MATERIALS AND METHODS

The study was carried out with a total of 40 infants, with a gestational age of 28-326 weeks, fed fresh (n = 20) or frozen (n = 20) breastmilk. Stool samples were stored at -80°C until analysis. Infants were included in groups based on the feed type, which accounted for more than 70% of their 10-day feeding. The Mann-Whitney U, Chi-square, and t-tests were used to evaluate the demographic data. Stool samples were analyzed by sequencing the V3--V4 region of the 16S rRNA gene from the extracted DNA for microbiota analysis.

RESULTS

Streptococcus and Enterobacteriales, the majority of which are considered human pathogens, in infants receiving frozen breastmilk (Streptococcus 69%, Enterobacteriales 79%) was higher than that in infants receiving fresh breastmilk (Streptococcus 16%, Enterobacteriales 49%). Further, the Lactobacillus and Bifidobacterium species were more abundant in infants who received fresh breastmilk (Lactobacillus 17%, Bifidobacterium 12%) than in infants who received frozen breastmilk (Lactobacillus 3%, Bifidobacterium 1%).

CONCLUSION

Thus, compared to frozen breast milk, fresh breastmilk has an effect on the diversity of preterm infants' gut microbiota.

Odor changes in breast milk during different storage temperatures and times using GC × GC-O-MS

Breastfeeding is generally the preferred way that most mothers will choose. It is common to store expressed breast milk in the refrigerator in many families. However, there is a phenomenon that infants may refuse to consume stored breast milk, presumably due to changes in odor. Thus, the odor changes in breast milk stored at 4 °C for 72 h and at -20 °C for 60 d were studied. Compared with fresh breast milk, 7 and 16 odor compounds were newly detected by SPME and GC × GC-O-MS when breast milk was stored at 4 and -20 °C, respectively. The concentration of (E)-2-decenal, octanal, hexanal, 1-octen-3-ol, 2-pentylfuran, lauric acid, decanoic acid and hexanoic acid significantly increased after storage at 4 °C for 36 h and -20 °C for 30 d. In addition, the proportion of acids increased, whereas that of aldehydes decreased during storage. Chemometric analysis with OPLS-DA suggested that breast milk should be stored at 4 °C for less than 36 h and at -20 °C for less than 30 d for maximum preservation of the original odors.

[The Effects of Breast Milk Olfactory Stimulation on Physiological Responses, Oral Feeding Progression and Body Weight in Preterm Infants]

PURPOSE

This study was conducted to evaluate the effect of breast milk olfactory stimulation on physiological responses, oral feeding progression, and body weight in preterm infants.

METHODS

A repeated measures design with nonequivalent control group was used. The participants were healthy, preterm infants born at a gestational age of 28~32 weeks; 12 in the experimental group and 16 in the control group. Data were collected prospectively in the experimental group, and retrospectively in the control group, by the same methods. Breast milk olfactory stimulation was provided 12 times over 15 days. The data were analyzed using the chi-square test, Mann-Whitney U test, Wilcoxon signed rank test and linear mixed models using SPSS 19.

RESULTS

The gastric residual volume (GRV) of the experimental group was significantly less than that of the control group. The heart rate, oxygen saturation, respiration rate, transition time to oral feeding, and body weight were not significantly different between the two groups.

CONCLUSION

These findings indicate that breast milk olfactory stimulation reduces GRV and improves digestive function in preterm infants without inducing distress.

Variations in the rancid-flavor compounds of human breastmilk under general frozen-storage conditions

BACKGROUND

Human breastmilk provides the best nutrition for infants. When women or infants have difficulties in breastfeeding directly, breastmilk is usually pumped and frozen for later use. However, while frozen, breastmilk may develop a rancid flavor, which induces infant feeding stress and raises the mothers' concerns about the quality of frozen breastmilk. Nevertheless, few studies have investigated the variations in the compounds that cause the rancid flavor of breastmilk during frozen storage.

METHODS

A repeated-measures design was adopted to quantify the variations in rancid-flavor compounds, namely acid value (AV), total free fatty acids (FFAs), and short-and intermediate-chain FFAs of breastmilk during frozen storage. Breastmilk was obtained from ten healthy mothers of full-term infants and each milk sample was divided into three aliquots: fresh, 7-day frozen and 30-day frozen samples. The fresh samples were immediately analyzed, while the others were frozen in a domestic fridge within a temperature range of -15 to -18 °C and analyzed 7 and 30 days later.

RESULTS

The rancid-flavor compounds of the breastmilk, namely AV, total FFAs and intermediate-chain FFAs, significantly increased with storage time, all of which reached the sensory threshold for detecting the rancid flavor of milk. In addition, the FFAs of the breastmilk samples frozen for 7 days far exceeded the detection threshold for unpleased rancid flavor, while the 30-day samples were higher than the intolerable level for most people.

CONCLUSIONS

This study revealed that the human breastmilk develops a rancid flavor during frozen storage. Therefore, we recommend that when infants refuse thawed milk, mothers can try to provide freshly expressed milk whenever possible or provide breastmilk frozen for less than 7 days. Future studies could explore the methods for slowing breastmilk lipolysis to maintain its fresh flavor.